Apparatus for and method of handling liquid metal



July 12, 1932. F, X, TEMMEN 1,866,682

APPARATUS FOR AND METHOD OF HANDLING LIQUID METAL Filed Nov. 8, 1928 3 Sheets-Sheet l INVENTOR M M F. X. TEMMEN July 12, 1932.

Filed Nov. 8, 1928 3 Sheets-Sheet INVENTOR F. X TEMMEN July 12, 1932.

APPARATUS 'F'OR AND METHOD OF HANDLING LIQUID METAL Filed Nov. 8, 1928 3 Sheets-Sheet 5 INVENTOR Patented July 12, 1932 UNITED STATES PATENT oi-Flca FRANK x. TEMMEN, OF COVINGTON, KENTUCKY, ASSIGNOB TO LAWRENCE C. TUB-N061,

O1? CLEVELAND HEIGHTS, OHIO APPARATUS NB AND METHOD OF HANDLING LIQUID METAL Application filed November 8, 1928. Serial 110. 817,845.

This invention relates to apparatus for and a method of handling liquid metal. It relates more particularly to a method and means for handling liquid metal, and at the same I time maintaining its temperature substantiall constant and high enough to prevent soli ification. The invention relates still more particularly to a novel liquid metal conveying apparatus, and to methods of util1z- 10 ing such apparatus in the production ot printing plates;

The problems arising in the handling of liquid metal are peculiar in that they require careful consideration of the high temperature 16 of the metal and its tendency to solidify upon cooling, its great weight and the unusual wear and depreciation of the handling equipment. These problems are capable of rather simple solution when the metal being handled is in l ver large uantities and is merely conveyed an poure from one vessel to another.

When, however, liquid or molten metal is handled in relatively small quantities wherein a much closer control of the metal flow is required, the problems above mentioned are much more difiicult of solution.

Liquid metal in small quantities has a greater tendency to solidify unless its temperature is maintained well above the solidi fication point, and even though it does not solidify, its viscosity varies considerabl with the temperature. .When small quantities are handled, it is therefore necessary to regulate very closely the temperature of the metal and to prevent it from solidifying or becoming excessively viscous, as by so doing it may damage the handling apparatus and interrupt the operation.

The above problems have particular application to the handlin of electrotype metal, stereotype metal, and like metallic alloys. However, the utility of my apparatus may be extended to the handling of metallic lead and many other metals, as well as alloys within certain flexible temperature ranges.

At times it is highl desirable to handle molten electrotype an stereotype metal in relatively small quantities, and its supply and rate of delivery must be regulated carefully and controlled within fairly close limits. Heretofore, electroty metal has been handled either by hand la ling or by allowing the molten metal to flow by gravity from a reservoir of molten metal to the delivery point through a conduit and manually controlled port opening lying below the surface of the main body of llquid metal.

For handling molten stereotype metal heretofore, in some cases a pump of the plunger type has been employed wherein the pump cylinder, closed at one end, is immersed in the molten metal bath, and the plunger operated manually is forced into the open cylinder end to displace the molten metal through a conduit to the delivery point. This method has certain limitations and disadvantages, to wit:

(1) It is manually operated and therefore subject to variation in the human element. v k

(2) It is not sufiiciently flexible to handle varying amounts of molten metal with regularit and accuracy. I

(23 The heights to which it can elevate the metal are more or less fixed by the nature of a plunger type of pump.

(4) It has a tendency to allow too much variation in temperature of the metal between the metal bath proper and delivery point.

(5) In manycommercial applications it would be impractical to operate it with any degree of satisfaction.

I provide a liquid metal conveying apparatus employing a rotatable screw operating in a conduit for substantially continuously feeding the metal through the conduit while the screw is in operation. I further provide heating means associated with the conduit for maintaining the metal at the desired temperature while it is being conveyed. I still further provide a method and means for backing up electrotype shells in the production of printing plates, wherein the casting pan and shell are heated by contact with the liquid metal and liquid electrotype metal subsequently poured into the pan to form the desired casting. The liquid metal conveying apparatus and heating means in accordance with my invention is likewise adaptable for making so-called stereotype casts.

In the accompanying drawings I have shown a present preferred embodiment of the invention, wherem Figure 1 is an elevational view, partly in crosssection, of a metal conveying apparatus;

Figure 2 is a top plan view, to somewhat larger scale, of the apparatus shown 1n Flgure 1 Figure 3 is a plan view of apparatus for handling metal; and

Figure 4 is an elevational view of a portion of the apparatus shown in Figure 3 Referring more particularl to Figures 1 and 2, reference number 2 esignates generally the outer shell of a receptacle for containing liquid metal. Disposed within the shell 2 is an inner lining 3, supported u on the shell at 4. The space between the s ell 2 and the lining 3 is filled with suitable heat insulating material such, for instance, as sil-o-cel powder. Located within the lin ng 3 are electrical heating elements 5, deriving their electrical energy from a suitable power source. The temperature of the metalbath is pyro-metrically re ulated through an automatic control pane (not shown) connectin heating elements 5 to the power source.

he receptacle is closed by a top 6 having suitable openings for the connections to the heating elements 5, a central circular opening 7 and a gauge opening 8. The receptacle is shown substantially filled with liquid metal in Figure 1, the float gauge 9 enabling the determination from without of the height of the metal within the receptacle.

Connected to a standard 10, mounted upon wheels 11, is a pair of upright supports 12. Carried by the supports 12 is a pinion 13 controlled through a shaft 14 by a hand wheel 15. Also mounted on the supports 12, and adapted for vertical movement with respect thereto, is a frame 16 having a rack 17 integral therewith. This rack meshes with the pinion 13 so that by operation of the hand wheel 15 the frame 16 may be raised and lowered with respect to the standard 10. The uprights 12 and the frame 16 are provided, respectively, with suitable holes 18 for the reception of ins or bolts to lock the frame 16 at desired eights.

Formed in the frame 16 is a circular recess 19 surrounded by an annular upraised flange 20. Mounted on the frame 16 is a carrier 21 having a vertical boss 22 received within the recess 19 of the frame and having an annular recess 22 adapted to embrace the flange 20 of the frame. A locking member 23 is provided on the carrier 21 to prevent it from losing engagement with the frame 16 while permitting rotation thereof about the center of the boss 19 and the recess 22. The carrier and frame are provided with a suitable segmental slot 24 for the reception of bolt 25, which, when located, prevents rotation of the carrier with respect to the frame. The segmental slot further provides a means permitting rotation of the ump mechanism degrees to either the rig t or left of center line.

Mounted upon the carrier is an electric motor 26 deriving its current from any suitable source of power (not shown) and controlled by a suitable rheostat (not shown in the usual manner. Upon the shaft 27 o the motor 26 is a bevel pinion 28. The extremit of keyed to the shaft 27 of the motor 26. Operation of the motor therefore causes rotation of r the shaft 32, such shaft being supported b the step bearing 31. Connected to the sha 32 is a conveying screw 34.

Surrounding the conveying screw 34 and adapted to pass throu h the central opening 7 in the cover 6 of the iquid metal receptacle is a conduit 35. This conduit is connected at its upper extremity to the step bearing 31 so that it does not rotate but permits rotation of the conveying screw 34 therein. The conduit 35 and screw 34 are adapted to extend downwardly into a body of llquid metal in the receptacle. The lower extremity of the screw 34 is rounded at 36 and fits within a lower bearing 37 carried by a suitable spider within conduit 35, and having a centrall disposed bearing ball 38. This bearing is buoyed up or maintained in cooperative relationship with the screw 35 by the liquid metal in the receptacle, its specific gravity being less than that of the liquid metal.

Such a bearing is found to materially assist in supporting the conve ing screw and preventing vibration thereo during operation. A substantially annular opening 39 is provided between the bearing 37 and the conduit 35 through which the molten metal is adapted to pass upon rotation of the screw, which rotation lifts the metal from the receptacle.

Surrounding the conduit 35 is a container 40 adapted to contain a bod of liquid 41 within which are suitable e ectric heating elements 42 deriving their current throu h conductors 43 from any suitable source. T e heating elements 42 heat the liquid in the container 40 and the liquid in turn imparts its heat to the conduit 35 and eventually through such conduit and to the liquid metal therein. The provision of a heating liquid within the container 40 enables a more uniform and closer tem erature control. Above the containt-r 40 t e conduit 35 is surrounded by an insulating covering 44.

If desired, the container 40 may comprise part of a circulating system leading from the ody of liquid metal in the receptacle and discharging thereto after passage through container 40. In such case the container 40 will be fed by a suitable overflow connection from the conduit 35.

Connected with the conduit 35 and extending generally laterally and downwardly there mm is a second conduit 45 surrounded by an insulating cover 46 having embedded therein an electric heating element 47 supplied with current through leads 48. The conduit 45 is provided at its outward extremity with trunnions 49 for a drip ladle 50.

The liquid metal raised by rotation of the conveying screw 34 passes through the conduit 45 and out through the spout at the end thereof. The flow of the metal is controlled by the speed of the motor 26 and may be as fast or as slow as desired within reasonable limits. During its conveyance from the receptacle through the conduits 35 and 45, the metal is maintained at the proper temperature by the heating elements 42 and 47 and the insulating covers 44 and 46. A close control is thus maintained over both the temperature and the flow of the liquid metal.

The conveying screw 34 terminates at its upper extremity substantially level with the bottom of the conduit 45 where such conduit enters the conduit 35. It has been found that when the screw extends substantially higher than this point, there is danger of metal becoming trapped within the conduit 35 above the conduit 45 and solidifying therein. When the conveying screw terminates at the point herein described, there is no positive forcing of the metal above the entrance to the conduit 45 except perhaps at very hi h speeds, but the flow of the metal is sufiicient y rapid at such speeds to revent it from cooling sufiiciently to solidi y.

t will be seen from Figure 1 that the frame 16 and carrier 21 together with the entire conveying apparatus may be raised and lowered on the uprights 12 by means of the rack and pinion. Furthermore, the conve ing apparatus-may be rotated as a whole about the pivotal connection 22 so as to enable it to be placed above a receptacle and then lowered thereinto. The standard 10 may, of course, also be transported on the wheels 11 so that a high degree of flexibility is obtained.

In Figure 4 is shown a pump generally similar to that of Figures 1 and 2, but to considerably reduced scale, and in which the bevel pinion and gear 28 and 33 are replaced by an adjustable clutch connection 51. This clutch connection comprises a friction disk 52 mounted upon the motor shaft and a cooperating friction roller 53 adapted to be moved to varying distances from the center of the shaft while still remaining in contact with the disk 52. The speed of rotation of the screw may therefore be controlled by the adjustable clutch connection or by the speed of the motor, or both, as desired.

There is also shown in Fi ure 4 a receptacle- 54 comprising a melting c amber 55 and a shallower chamber 56 adapted to hold a bath of liquid metal and to receive shells which are dipped therein, as will be presently descrlbed. Between the chambers 55 and 56 is a baflie 57 providing an opening 58 between the chambers and below the surface of the liquid metal contained therein so that liquid metal may flow between the chambers while pieces of unmelted metal, dross and the like, which float upon the surface, are effectively maintained in the melting chamber 55.'

Pieces of metal are charged into the chamber 55 where they are melted and the liquid thus has free access to the shallower chamber 56. A casting pan 59 is adapted to be placed in the liguid metal bath in the chamber 56 to be heate thereby. Such casting pan is removed after being heated, and metal may be pumped outof the chamber 55 by the pump shown and poured into the previously heated casting pan 59 for producing a cast ng such as a printing plate. The liquid metal therefore serves a two-fold purpose, namely, first to heat the casting pan, and second to be ploured into the casting pan to complete the p ate.

In Figure 3 is shown a receptacle similar to that of Figure 4 and havinga melting chamber 55 and a bath chamber 56. A pump 60 pumps metal from the chamber 55 into a separate heating chamber 61 which is maintained ata very closely regulated temperature, so that the temperature of the liquid metal may be closely controlled thereby. From the heating chamber 61 the liquid metal is pumped by another pump 62 into casting pan molds or the like previously heated by contact with the metal bath in thechamber 56. A suitable conveyor 63 is provided for moving the completed casting pan or the like from the casting station.

In dotted lines in this figure I hayve indicated the pump 60 as discharging directly into the casting pan on the casting rack or conveyor 63. This serves to illustrate the flexibility of the present invention, and indicates how in an emergency, as in case of injury to the pump 62, the apparatus may be continued in operation.

By reason of the provision of continuous screw conveyors, a substantially steady and uniform flow of metal may be maintained from the chamber 55 to .the chamber 61 and thence to the molds. At the same time the temperature of the metal is adapted for close regulation, thereby providing a most satisfactory method for casting the plates. Little or no difliculty will be experienced with metal freezing in any part of the system by by first using the liquid metal to heat the molds and then using the same metal for casting.

Due to the position of the screw and the pitch of its blades, any metal within the conduit 35 above the level of the bath will flow downwardly upon cessation of rotation of the screw and will not freeze within the upper portion of the conduit. In like manner, the inclination of the spout precludes the accumulation of metal therein.

While I have shown and describedcertain present preferred embodiments of the invention, it is to be understood that the same is not limited thereto, but ma be otherwise embodied and practiced within the scope of the following claims.

I claim 1. In the method of casting, the steps comprising uniformly elevating a column of liquid metal to substantially the plane of a discharge outlet, permitting the metal to flow by gravity through such outlet directly into a mold, and controlling the quantity of metal delivered to the mold by controlling the elevation of the metal.

2. In liquid metal conveying apparatus, a conduit, a rotatable screw therein having a rounded lower extremity, and a floating thrust bearing having a portion embracing the rounded extremity of the screw and adapted to be maintained in operative relation with the screw by the upward force of the liquid metal thereagainst.

3. In liquid metal conveying apparatus. a generally upright conduit, a rotatable lifting screw therein. a step bearing for the upper extremity of the screw, a second conduit connected with the first and extending generally laterally and downwardly therefrom, and heating means associated with the conduits for maintaining the metal being conveyed in a liquid state, the screw terminating immediately below the connection between the two conduits to prevent freezing of the metal against the relatively cool step bearing.

4. In liquid metal conveying apparatus, a generally upright conduit, a rotatable lifting screw therein. a step bearing for the upper extremity of'the screw, and a floating bearing for the lower extremity of the screw adapted to be maintained in operative relation with the screw by the upward force of the liquid metal thereagainst.

5. In liquid metal conveying apparatus, a support, a motor mounted thereon for vertical and pivotal movement and a rotatable screw connected to the motor to be operated 0 thereby for lifting liquid metal from a reservoir.

6. In liquid metal conveying apparatus, a rotatable screw, means for lowering'the screw into a reservoir of liquid metal, driving means for the screw, and an adjustable clutch 1,ace,oaa

connection between the driving means and screw whereby the s eed of rotation of the screw may be contro ed to alter the rate at which the li uid metal is conveyed independently of t e speed of the driving means.

7. Apparatus for casting metal, comprising a rece tacle for receiving pieces of metal to be me ted, a receptacle communicating therewith and provi in a metal bath for heating solid objects p aced therein, and means for confining unmelted pieces of metal and dross in the second race tacle while permitting circulation of liquid metal between the two receptacles.

8. Apparatus for casting metal, comprising a receptacle having a melting chamber and a chamber communicating therewith providing a bath for heating a mold placed therein, a second receptacle for receivin liquid metal from the first receptacle and maintaining it at a substantially constant temperature, and means for pouring such liquid metal from the second receptacle into the heated mold.

9. Apparatus for casting metal, comprising liquid metal receptacles communicating below the liquid level and separated at the liquid level, one of said receptacles bein of relatively large superficial area and she ow in depth, and means for heating said receptacles.

10. In a method of casting, the steps comprising melting a mass of metal, transferring portions of said molten metal to a secondary supply, maintaining said secondary supply at a uniform tem rature, uniformly pum ing liquid metal rom said secondary supp y and discharging the same directly into a mold, and controlling the quantity of metal supplied to the mold by controlling the operatlon of pumping the metal.

11. In liquid metal conveying apparatus, a conduit, a rotatable screw therein, and a floating bearing for the lower end of the screw maintained in operative relation with the screw by the upward force of the liquid metal therea ainst.

12. In liquid metal conveying apparatus, a rotatable screw, a casing therearound, and a floating ball bearing for the lower end of the screw slidably received in the casing.

13. In liquid metal conveying apparatus, a support, conveying means pivotally mounted on said support to swing about a vertical axis comprising a delivery conduit extending generally laterally and downwardly, and a pump for elevating liquid metal thereto comprising a generally upright conduit and a rotatable lifting screw therein, said upright conduit communicating with said delivery conduit.

In testimony whereof I have hereunto set my hand.

FRANK X. TEMMEN. 

